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Abstract:

A segmented polarizing device may be a polarizing modulator which may
include strips of switching polarizer material. The switching polarizer
material may be used to switch individual segments of the polarizing
modulator at a time. In such devices, the polarizing modulator may be one
or more liquid crystal cells (LC cell). As the LC modulation panel of a
display refreshes an image from top to bottom, changing from left eye
content to right eye content, the polarization of a corresponding part of
a scrolling polarizing screen may change along with the display.

Claims:

1. A segmented polarization device for a projector comprising: a
segmented polarization modulator comprising a plurality of polarization
switching elements operable to selectively transform the state of
polarization of incident modulated light.

3. The segmented polarization device of claim 2, wherein the strips of
switching polarizer material are operable to switch individual strips of
the segmented polarization modulator at a time.

4. The segmented polarization device of claim 2, wherein each of the
strips of switching polarizer material are vertical strips and the
plurality of polarization switching elements comprises one or more liquid
crystal cells.

5. The segmented polarization device of claim 2, wherein the strips of
switching polarizer material are operable to refresh an image on a
display from the top to the bottom which may change the display from a
first mode to a second mode.

6. The segmented polarization device of claim 5, wherein a first half of
the display is in the first mode and a second half of the display is in
the second mode.

7. The segmented polarization device of claim 2, wherein the strips of
switching polarizer material are operable to selectively transform the
state of polarization of incident modulated light.

8. The segmented polarization device of claim 7, wherein the state of
polarization is transformed between substantially orthogonal polarization
states.

9. The segmented polarization device of claim 1, wherein a voltage
applied to the segmented polarization modulator modulates the state of
polarization of incident light.

10. The segmented polarization device of claim 2, wherein the strips of
the switching polarizer material are operable to switch polarization
states, wherein the switching is timed to substantially coincide with a
blank set of images lines on a display that provide a dark period in a
frame sequence.

11. The segmented polarization device of claim 1, wherein the plurality
of polarization switching elements are arranged in a quadrant pattern to
form an optical window.

12. A method of stereoscopic projection, the method comprising: operating
a segmented polarization switch in a scrolling mode by sequentially
switching individual polarization switching elements that are
substantially synchronized with a frame sequence of a projector.

13. The method of claim 12, further comprising inserting a blank set of
image lines in the frame sequence.

14. The method of claim 13, wherein inserting the blank set of image
lines further comprises providing a dark period wherein the dark period
is a fraction of an image frame cycle time.

15. The method of claim 14, further comprising timing the dark period to
substantially coincide with the polarization state switching of each
segment of a segmented modulator.

16. The method of claim 13, wherein inserting the blank set of images
lines in the frame sequence further comprises blanking a small section of
the display while a corresponding, aligned segment of a modulator
switches polarization states.

17. A method for stereoscopic projection, the method comprising:
providing a segmented polarization modulator comprising a plurality of
polarization switching elements operable to selectively transform the
polarization state of incident light, wherein the segmented polarization
modulator further comprises strips of switching polarization material
operable to switch individual segments of a polarizing modulator.

18. The method for stereoscopic projection of claim 17, further
comprising refreshing an image on a display from the top to the bottom
and changing from a first mode to a second mode, wherein refreshing the
image is coordinated with switching individual segments of the polarizing
modulator.

19. The method for stereoscopic projection of claim 17, further
comprising inserting a blank set of image lines in a frame sequence and
timing the blank set of images lines to substantially coincide with the
polarization state switching of each segment of a segmented modulator.

20. The method for stereoscopic projection of claim 18, further
comprising transforming the state of polarization of the incident light
passing through the segmented polarization modulator from a first
polarization state to a second polarization state, wherein the second
polarization state is substantially orthogonal to the first polarization
state.

[0002] This disclosure generally relates to stereoscopic projection using
polarized light, and more specifically relates to scrolling, segmented
polarization modulation of light for stereoscopic projection in cinema,
professional and home environments.

BACKGROUND

[0003] In the last few years stereoscopic 3D projection has been
accomplished with either digital light processing (DLP) imaging devices
or with liquid crystal display/liquid crystal on silicon (respectively,
LCD/LCOS) imaging devices. These devices work by projecting a sequence of
substantially still images with each image projected for a short amount
of time.

[0004] The DLP imaging devices can be switched substantially
instantaneously and/or refreshed in as little as 200 microseconds. During
the refresh time the display may be blanked for a period of time such
that little light exits the projector, but the lamp may stay on. After
the refresh, the display is unblanked, and the image of each frame may be
projected for the remainder of the frame cycle, which is about 6.7
milliseconds in the case of 144 Hz projection for digital cinema. This
allows the viewer to perceive a bright image of each frame. Left and
right eye images are presented one after the other in a frame-sequential
manner. A high frame rate is desired when projecting frame sequential 3D
stereoscopic presentations so that the image retention characteristics of
the human eye will perceive a continuous sequence of images in each eye.
The high frame rate also places the left and right frames closer in time,
which minimizes motion induced disparity errors. Each frame for each eye
is presented twice or three times, which is known as double or triple
flashing, in order to achieve the high frame rate needed for the
perception of a continuous image in each eye.

[0005] For use with single DLP projectors during 3D stereoscopic
presentations, RealD Inc. and other manufacturers offer various
polarization switching modulators. By way of example, such polarization
switching modulators are described in commonly-owned U.S. Pat. Nos.
4,792,850, 7,760,157, and 7,528,906, all of which are herein incorporated
by reference in their entirety. When a left eye image is being projected,
the polarization switching modulator is set to globally encode the
presented polarization state to left eye polarity. During the blanking
interval, while the projector is refreshing the imager with the opposite
eye image, the polarization switching modulator globally switches to the
right eye polarity. This sequence of switching polarity is continued as
the projector alternately displays left and right eye images. The
switching of the modulator is timed with a signal from the projector.
Modulators such as the RealD polarization switching modulator, switch
using a liquid crystal cell which has a very fast response time. Other
known techniques for polarization switching use mechanical switching
methods, such as a polarization wheel.

[0006] LCD/LCOS imaging devices may not be able to refresh as quickly as a
DLP imaging device. The LCD/LCOS imaging device may employ most of the
6.7 millisecond frame exposure time mentioned above just to refresh the
image for a single frame. If the lamp is blanked during the refresh time,
there will not be very much of the total cycle time remaining The
exposure time may not be sufficient to allow the viewer to perceive a
good, bright image. Therefore, LCD/LCOS imagers have not been used for
single projector frame sequential 3D presentation which is a serious
disadvantage for LCD imaging technology. Instead, they are used in other
creative ways such as in dual projector configurations where each
projector runs at a normal 24 fps frame rate and each projector displays
a separate eye view of the stereoscopic presentation. While this method
works, it requires two projectors and is also disadvantaged by alignment
and light balancing requirements.

BRIEF SUMMARY

[0007] According to the present disclosure, a segmented polarization
device for a projector may include a segmented polarization modulator.
The segmented polarization modulator may be a plurality of polarization
switching elements operable to selectively transform the state of
polarization of incident modulated light. Also, the plurality of
polarization switching elements may be strips of switching polarizer
material that may be operable to switch individual segments of the
segmented polarization modulator at a time. Each of the strips of
switching polarizer material may be vertical strips and may be one or
more liquid crystal cells. Additionally, the strips of switching
polarizer material may be operable to refresh an image on a display from
the top to the bottom which may change the display from a first mode to a
second mode. Further, a first half of the display may be in the first
mode and a second half of the display may be in the second mode.

[0008] Furthering the discussion of the strips of switching polarizer
material, the strips may be operable to selectively transform the state
of polarization of incident modulated light between substantially
orthogonal polarization states. A voltage may also be applied to the
segmented polarization modulator which may modulate the state of
polarization of incident light. The strips of the switching polarizer
material may be operable to switch polarization states, in which the
switching may be timed to substantially coincide with a blank set of
images lines that provide a dark period in a frame sequence. In one
example, the plurality of polarization switching elements may be arranged
in a quadrant pattern to form an optical window.

[0009] According to another aspect of the present disclosure, a method of
stereoscopic projection may include operating a segmented polarization
switch in a scrolling mode by sequentially switching individual
polarization switching elements that may be substantially synchronized
with a frame sequence of a display. The method of stereoscopic projection
may also include inserting a blank set of image lines in the frame
sequence which may include providing a dark period wherein the dark
period may be a fraction of an image frame cycle time. Inserting the
blank set of images lines in a frame sequence may also include blanking a
small section of the display while a corresponding, aligned segment of a
modulator switches polarization states. Additionally, the method may
include timing the dark period to substantially coincide with the
polarization state switching of each segment of a segmented modulator.

[0010] According to yet another aspect of the present disclosure, a method
for providing a polarization device may include providing a segmented
polarization modulator which may include a plurality of polarization
switching elements operable to selectively transform the polarization
state of incident light. The segmented polarization modulator may further
include strips of switching polarization material operable to switch
individual segments of a polarizing modulator. The method may also
include refreshing an image on a display from the top to the bottom and
changing the display from a first mode to a second mode, wherein
refreshing the image may be coordinated with switching individual
segments of the polarizing modulator. Additionally, the method may
include selectively transforming the polarization state of incident light
after the incident light passes through the segmented polarization
modulator. Moreover, the method may further include transforming the
state of polarization of the incident light passing through the segmented
polarization modulator from a first polarization state to a second
polarization state, in which the second polarization state may be
substantially orthogonal to the first polarization state.

[0011] These and other advantages and features of the present disclosure
will become apparent to those of ordinary skill in the art upon reading
this disclosure in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Embodiments are illustrated by way of example in the accompanying
figures, in which like reference numbers indicate similar parts, and in
which:

[0013]FIG. 1 is a schematic diagram illustrating a top down view of a
stereoscopic projector system projecting an image on a screen, in
accordance with the present disclosure;

[0014]FIG. 2 is a schematic diagram illustrating one embodiment of a
segmented polarization switch, in accordance with the present disclosure;
and

[0015]FIG. 3 is a schematic diagram illustrating another embodiment of a
segmented polarization switch, in accordance with the present disclosure.

DETAILED DESCRIPTION

[0016] Generally, a segmented polarization device may include a segmented
polarization modulator. The segmented polarization modulator may be a
plurality of polarization switching elements operable to selectively
transform the state of polarization of incident modulated light. Also,
the plurality of polarization switching elements may be strips of
switching polarizer material that may be operable to switch individual
segments of the segmented polarization modulator at a time. Each of the
strips of switching polarizer material may be vertical strips and may be
one or more liquid crystal cells. Additionally, the strips of switching
polarizer material may be operable to refresh an image on a display from
the top to the bottom which may change the display from a first mode to a
second mode. Further, a first half of the display may be in the first
mode and a second half of the display may be in the second mode. The
strips of switching polarizer material may be operable to selectively
transform the state of polarization of incident modulated light between
substantially orthogonal polarization states. A voltage may also be
applied to the segmented polarization modulator which may modulate the
state of polarization of incident light. The strips of the switching
polarizer material may be operable to switch polarization states, in
which the switching may be timed to substantially coincide with a blank
set of images lines that provide a dark period in a frame sequence.

[0017] Additionally, a method of stereoscopic projection may include
operating a segmented polarization switch in a scrolling mode by
sequentially switching individual polarization switching elements that
may be substantially synchronized with a frame sequence of a projector.
The method of stereoscopic projection may also include inserting a blank
set of image lines in the frame sequence which may include providing a
dark period wherein the dark period may be a fraction of an image frame
cycle time. Inserting the blank set of images lines in a frame sequence
may also include blanking a small section of the display while a
corresponding, aligned segment of a modulator switches polarization
states. Additionally, the method may include timing the dark period to
substantially coincide with the polarization state switching of each
segment of a segmented modulator.

[0018] According to yet another aspect of the present disclosure, a method
for providing a polarization device may include providing a segmented
polarization modulator which may include a plurality of polarization
switching elements operable to selectively transform the polarization
state of incident light. The segmented polarization modulator may further
include strips of switching polarization material operable to switch
individual segments of a polarizing modulator. The method may also
include refreshing an image on a display from the top to the bottom and
changing the display from a first mode to a second mode, wherein
refreshing the image may be coordinated with switching individual
segments of the polarizing modulator. Additionally, the method may
include selectively transforming the polarization state of incident light
after the incident light passes through the segmented polarization
modulator. Moreover, the method may further include transforming the
state of polarization of the incident light passing through the segmented
polarization modulator from a first polarization state to a second
polarization state, in which the second polarization state may be
substantially orthogonal to the first polarization state.

[0019] It should be noted that embodiments of the present disclosure may
be used in a variety of optical systems and projection systems. The
embodiment may include or work with a variety of projectors, projection
systems, optical components, displays, microdisplays, computer systems,
processors, self-contained projector systems, visual and/or audiovisual
systems and electrical and/or optical devices. Aspects of the present
disclosure may be used with practically any apparatus related to optical
and electrical devices, optical systems, presentation systems or any
apparatus that may contain any type of optical system. Accordingly,
embodiments of the present disclosure may be employed in optical systems,
devices used in visual and/or optical presentations, visual peripherals
and so on and in a number of computing environments.

[0020] Before proceeding to the disclosed embodiments in detail, it should
be understood that the disclosure is not limited in its application or
creation to the details of the particular arrangements shown, because the
disclosure is capable of other embodiments. Moreover, aspects of the
disclosure may be set forth in different combinations and arrangements to
define embodiments unique in their own right. Also, the terminology used
herein is for the purpose of description and not of limitation.

Segmented Polarization Modulators for Stereoscopic Projection

[0021] The present disclosure enables frame-sequential 3D projection with
single projectors based on LCOS or LCD imaging devices.

[0022] Generally, cinema projectors based on LCOS imagers have projected
both left and right images simultaneously. An imaging chip used in this
system may have a 4096×2160 resolution and as a result, the two
images are placed one over the other on the imaging chip at the same
time. Because the projector spreads the lamp light over the entire
imaging chip, this method results in significant light loss since not all
pixels can be used to form the image. Also, this method requires a
complex and expensive lens that splits the image in two halves, polarizes
them oppositely from each other, and then joins the two images on the
projection screen.

[0023] Additionally, known conference room projectors using LCD imagers
may not have enough resolution to use the cinema approach of placing one
image over the other. Thus, for a 3D presentation, they must be
configured in a dual projector setup, where one projector displays the
left eye content and the other projector displays the right eye content.
The left and right eye content may present views for the left and right
eye respectively. The dual projector setup involves extra cost of a
second projector, synchronizing the signal to each projector and aligning
the images on screen and balancing the light output and colors of both
projectors. The teachings of the present disclosure may allow for a
single projector to be used, eliminating extra cost and the
synchronization and alignment operations. Thus, the ability to do single
projector 3D with these projectors will be presented herein.

[0024] The teachings within the present disclosure described here may
allow more pixels to be used, increasing the light output and resolution
of the projected image. For example, on a 4K imaging device, the change
from substantially simultaneous frame presentation to frame sequential
presentation may increase the number of pixels used by 4× in the
case of 2.39:1 aspect ratio content. A 4K imaging device may be an
imaging device that produces an image that is approximately 4096 pixels
wide. Additionally, although the horizontal resolution may remain
substantially the same, the vertical resolution may vary with the aspect
ratio. For example, a 2K image with a 16:9 aspect ratio may be
2048×1152 pixels while a 2K image with a 4:3 aspect ratio may be
2048×1536 pixels, while a 2K image with a 2.39:1 aspect ratio may
be 2048×856 pixels. Increased usable light may indicate that a
projector may provide a brighter image to the viewer, provide images to a
larger screen, or both. Another key advantage is that the same single
lens can be used for 3D as for 2D movies, eliminating the difficult lens
change operation that is currently required. This disclosure will allow
LCOS cinema projectors to display single projector 3D with much more
light output, less cost and much easier installation and operation
procedures. Continuing the example with 2.39:1 aspect ratio content, the
light per eye may be approximately doubled when compared to the
simultaneous frame presentation method.

[0025] The present disclosure provides a segmented scrolling polarizer for
projectors such as, but not limited to, a LCD/LCOS projector. Although
some of the embodiments discussed herein may refer specifically to a
LCD/LCOS projector, this is for discussion purposes only and not of
limitation. Embodiments disclosed herein may be implemented with any
display, projector, or imaging device that refreshes images row by row.
In one example, a scanned projector may be employed such as, but not
limited to a scanned laser projector.

[0026] Further, although the term segmented scrolling polarizer may be
used for discussion purposes, the segmented polarizer may benefit
projectors that update a display on a scrolling or block basis. Moreover,
additional schemes may be employed in which the update may scroll from
the centerline up and down substantially simultaneously, or may update
from left to right, right to left, from the center line to the left and
right substantially simultaneously, and so on. In one example, a CRT
display or any display that may refresh rows from top to bottom or vice
versa may be employed with the segmented scrolling polarizer. Moreover,
any type of self-illuminated projector may be employed with the segmented
scrolling polarizer, including, but not limited to, CRT, scanned laser,
OLED, any modulator based projector, and so on. A benefit of the
technique provided in this disclosure may be accommodating slower refresh
rates, as opposed to the refresh timing that existing polarization
modulators can be used with. This may allow, for example, LCD/LCOS type
imaging devices such as, but not limited to, light modulating panels,
displays, microdisplays, projection systems such as, but not limited to
OLED projection systems, optical systems and so on, to be used for single
projector frame sequential stereoscopic projection.

[0027]FIG. 1 is a schematic diagram illustrating a top down view of a
stereoscopic projection system projecting an image on a screen. In FIG.
1, stereoscopic projection system 100 may include a projector 110 and a
segmented polarization switch 120 projecting an image on a screen 140.
Additionally, segmented polarization switch 120 may be located outside or
inside the lens 116. In one example, the segmented polarization switch
120 may be located on the LCOS modulation panel 114 (not illustrated in
FIG. 1). Source 105 provides image information to the projector 110.
Source 105 may be a DVD, Bluray, computer, internet-enabled device,
set-top box, or any other device that may provide electronic image
content for presentation. Lamp 112 in projector 110 may illuminate LCD or
LCOS modulation panel 114. It should be appreciated that various
different projection engine technologies that incorporate LCD or LCOS
modulation techniques may be employed, for example, reflective and
transmissive modulation panels, and such various LCD/LCOS projection
engines are not exhaustively discussed or illustrated for simplicity of
the present description.

[0028] In common use a polarizing switch may be a single window which
changes polarity uniformly across the optical window. A segmented
polarization switch may utilize small segments which may change
polarization state individually or in combination, allowing localized
control of the polarity of the image for individual or multiple segments
of the image. In one example, LC cells may be placed adjacent to or next
to each other to form segments. In contrast, a standard polarization
switch may switch the polarity of the entire window at the same time.

[0029] In another example, polarizing segments may substantially span the
width of the optical window and may be arranged vertically. With that
said, the polarizing strips may also be vertical strips that may be
arranged horizontally to form an optical window. The polarizing segments
may also be one or more LC cells. Further, each strip may be any type of
polarizing switching material, including, but not limited to, an
individual liquid crystal cell (LC cell), a pair of LC cells, pi-cells,
FLC, TN cells, single or push pull TN or Pi-cells, STN, mechanical and so
on.

[0030] Additionally, the optical window may include polarizing material in
various configurations including, but not limited to, dividing the
optical window into quadrants, radial segments, concentric patterns, or
any other pattern and the strips may be switched sequentially for any
configuration. These alternative arrangements may be employed with a
display that may refresh an image in a non-vertical pattern. Furthermore,
the polarizing material may be referred to herein as strips for
discussion purposes only and not of limitation. The polarizing material
may be any shape or configuration and arranged in various ways to produce
any shape of an optical window.

[0031] Segmented polarization switch 120 may be placed in the light path
in front of the projector lens 116 and may be operated in a scrolling
mode of operation. The image from the projector may be properly aligned
relative to the segments in the segmented polarization switch 120.
Further, the segmented polarization switch 120 may be properly aligned by
minimizing the amount of cross-talk between the left and right eye
images. Each segment of the segmented polarization switch 120 may be
switched to an opposite polarity as the image in the projector is
updated, line by line from top to bottom. This may allow projectors with
slow refresh rates to present frame sequential stereoscopic 3D content in
cases where the refresh rate is too slow to work with a switching
polarizer that switches the entire modulator at once.

[0032]FIG. 2 is a schematic diagram illustrating another segmented
polarization switch 200. Segmented polarization switch 200 includes
polarization switching segments 210, 220, 230, 240, 250, 260, each of
which may be controlled to transform the state of polarization according
to the bias voltage applied. In one example, a bias voltage may be
applied to each of the polarization switching segments starting with the
polarization switching segment 210, then to polarization switching
segment 220, and so on. As the bias voltage is applied to the
polarization switching segment, the state of polarization of the light
incident to the switch may switch as well.

[0033] Control of each polarization switching element may be performed by
a controller within projector 110, or from an external controller that
may synchronize with source 105 and/or projector 110. The segmented
polarization control segments 122, 123, 124, 125, 126 may be operable to
selectively transform the state of polarization (SOP) of the modulated
light incident from the projection lens 116 between orthogonal
polarization states according to the polarization control instructions
applied to each segmented polarization control segment. Although six
segmented polarization control segments are shown here for illustrative
purposes, it should be appreciated that the number of polarization
switching segments may vary, and six are shown merely for illustrative
and discussion purposes only.

[0034] In one example, a segmented polarization switch may present a frame
sequence and may include a series of right eye content and left eye
content. A blank set of image lines can be inserted in the frame sequence
to provide a dark period. This dark period, which may be a fraction of
the image frame cycle time, can be timed to substantially coincide with
the polarization state switching of each segment of the segmented
modulator. This approach may prevent blurring of the image as the
polarization switches from one polarization state to another. Instead of
blanking the entire image while a single polarizer switches state, the
segmented polarization switch may blank a small section of the display
while a small segment of the modulator switches state.

[0035] One aspect of the disclosure may include alignment of the segmented
polarization switch with the image exiting the projector. This can be
accomplished in many ways. In one example, the modulator opening may be
approximately the same aspect ratio as the imaging device, which for
cinema content may be approximately 1.9 to 1. Additionally, the modulator
opening may be other aspect ratios depending on the content. In another
example, the aspect ratio of the modulator opening may be approximately
1.8:1 for HD content. Returning to the example for cinema content and a
1.9:1 aspect ratio for the modulator opening, the entire imaging chip may
fit tightly within the operating area of the segmented modulator. This
may allow different sized content to be displayed while maintaining the
correct timing between the segments of the display and the refreshing
image, so long as the entire imaging chip is refreshed on every frame
cycle.

[0036] The present disclosure provides for single LCD/LCOS projectors to
present frame-sequential content for the first time. Frame-sequential
presentation is desirable because it may allow a single projector to be
used for 3D content. This may eliminate the alignment and optical
balancing challenges of a dual projector system. It may also allow the
entire imaging chip to be used, which may not be possible when left and
right eye images are presented side-by-side on a single imager, which is
another approach in current use.

[0037] To use this device, the LCD/LCOS imager may refresh fast enough
that the human eye does not perceive flicker. For content that is
recorded at approximately a nominal 30 fps, which is typical of broadcast
content, a total of approximately 60 frames per second may be presented
for a 3D presentation. This content may be double flashed resulting in
approximately 120 refresh cycles per second.

[0038] For content that is recorded at approximately a nominal 24 frames
per second, which is typical of motion picture content, a total of
approximately 48 frames per second may be presented for a 3D
presentation. This content at double flash may result in approximately 96
flashes per second, which may not be fast enough to eliminate the
perception of flicker. The content can be triple flashed for a total of
approximately 144 flashes per second, which is approximately 6.9 msec per
frame cycle. Another option for approximately 24 fps content is to use an
approximately 5:2 frame multiple which may effectively multiply by 2.5
flash. This may result in approximately 120 frames per second or
approximately 8.33 msec per frame cycle. In general, it may be
appropriate to use the highest frame rate multiple that the projector can
accommodate.

[0039] The teachings of U.S. patent application Ser. No. 12/853,273,
entitled "Improved segmented polarization control panel," filed Aug. 9,
2010, which is herein incorporated by reference in its entirety, may be
utilized to reduce potentially visible segment boundaries caused by the
`dead` regions between each polarization control segment.

Scrolling Polarizing Direct-View Screen

[0040] A scrolling polarizing screen may be used in conjunction with
direct-view LCD displays, as may be described in U.S. patent application
Ser. Nos. 12/156,683 and 12/853,274, both of which are herein
incorporated by reference.

[0041] In some cases, a scrolling polarizing screen may be a polarizing
modulator and horizontal, vertical or any shape of strips of switching
polarizer material may be used to switch individual segments of the
polarizing modulator at a time. In such devices, each strip may be any
type of polarizing switching material, including, but not limited to, an
individual liquid crystal cell (LC cell), a pair of LC cells, pi-cells,
FLC, TN cells, single or push pull TN or Pi-cells, STN, mechanical and so
on.

[0042] In one example, as the LC modulation panel of a display refreshes
the image from top to bottom, changing from left eye content to right eye
content, the polarization of a corresponding part of a scrolling
polarizing screen may change along with the display. It is possible with
this technique for part of the display to present left eye content while
the other part of the display presents right eye content. This is
illustrated in FIG. 3, where the upper half of the display is in right
eye mode and the lower half is in left eye mode.

[0043] This display may work with any content at any frame rate so long as
the frame rate is fast enough to be viewed in a frame-sequential manner.
Typically this frame rate should be more than the flicker fusion
threshold of approximately 110 frames per second at theatrical brightness
levels, or approximately 55 frames per eye, to reduce the perception of
flicker. Flicker may be perceived with frame sequential projection at
lower frame rates because each eye sees alternating light and black.
Stated differently, while one eye is exposed with light, the other is
seeing black.

[0044] As may be used herein, the terms "substantially" and
"approximately" provide an industry-accepted tolerance for its
corresponding term and/or relativity between items. Such an
industry-accepted tolerance ranges from less than one percent to ten
percent and corresponds to, but is not limited to, component values,
angles, et cetera. Such relativity between items ranges between less than
one percent to ten percent.

[0045] While various embodiments in accordance with the principles
disclosed herein have been described above, it should be understood that
they have been presented by way of example only, and not limitation.
Thus, the breadth and scope of the embodiment(s) should not be limited by
any of the above-described exemplary embodiments, but should be defined
only in accordance with any claims and their equivalents issuing from
this disclosure. Furthermore, the above advantages and features are
provided in described embodiments, but shall not limit the application of
such issued claims to processes and structures accomplishing any or all
of the above advantages

[0046] Additionally, the section headings herein are provided for
consistency with the suggestions under 37 CFR 1.77 or otherwise to
provide organizational cues. These headings shall not limit or
characterize the embodiment(s) set out in any claims that may issue from
this disclosure. Specifically and by way of example, although the
headings refer to a "Technical Field," the claims should not be limited
by the language chosen under this heading to describe the so-called
field. Further, a description of a technology in the "Background" is not
to be construed as an admission that certain technology is prior art to
any embodiment(s) in this disclosure. Neither is the "Summary" to be
considered as a characterization of the embodiment(s) set forth in issued
claims. Furthermore, any reference in this disclosure to "invention" in
the singular should not be used to argue that there is only a single
point of novelty in this disclosure. Multiple embodiments may be set
forth according to the limitations of the multiple claims issuing from
this disclosure, and such claims accordingly define the embodiment(s),
and their equivalents, that are protected thereby. In all instances, the
scope of such claims shall be considered on their own merits in light of
this disclosure, but should not be constrained by the headings set forth
herein.